k1 = (H^+)(HA^-)/(H2A)
Substitute and solve for x = (H^+) and convert to pH. Note that the k2 is about 100 times smaller than k1 so ignoring k2 doesn't cause much error.
I obtained 0.0787M for (H2A--you can round to correct sig figures) and for A^2- it is done this way.
k2 = 5.5E-7 = (H+)(A^=)/(HA^-). Since (H^+) = (HA^-), then (A=) = k2.